The author makes a point that I hadn't really thought much about; namely, that observing the mayhem is itself entertaining to a large number of people, which in turn drives site owners to, at the very least unconsciously, permit nearly uncontrolled ass-hattery, in exchange for eyeballs and advertising revenue.
JoS seems to have maintained a decent signal-to-noise ratio; let's hope that Hacker News manages to do so as well.